Architectural elements

Known at least since the 3rd dynasty, true arches were rarely used in early Ancient Egypt. Only when the building material was mud bricks and building corbelled vaults was impractical, were true arches erected.
In Djoser's great mastaba a barrel-vault has been found. It was built with bricks wedged together and bonded from above with gravel and mortar.
In the 12th dynasty pyramid at Hawara a brick arch almost a metre thick was erected above the rock burial chamber and passages, separating and supporting the upper part of the pyramid consisting of bricks laid in sand and a limestone covering, which has completely disappeared.
It was only the Romans who succeeded in integrating arches and using them in a grand manner.

Doorways were generally built with stone lintels, though W.M.Flinders Petrie found evidence for arched doorways as well as for vaulted roofs made of bricks at the 12th dynasty city Hotep-Senusret.
Bricks used in arches were thinner, lighter and at times wedge shaped. Holes scored into them with fingers during production improved their bonding together when they were laid.[7]

Architraves (from Latin trabs, beam) are the main beams resting across the tops of the columns. In ancient Egypt no attempts were made to cover pillared halls with arches. In the temple symbolism the architraves were part of the heavens.

Corbels were widely used in stone buildings; and corbelled arches continued to be constructed a long time after the true arch had been invented. They can be found in pyramids and occasionally in temples. The use of corbelled instead of true arches limited the width that could be spanned, but required less dressing of stones.

In tombs and temples for the dead there were niches for offerings, the back walls of which were given the form of
doors. They served as a pathway between the living and the dead by which the Ka and the other spiritual parts of the deceased could communicate with the world of the living. The nourishment that was offered to the dead, could be real food placed on an offering slab or symbolic food carved into a stela. The earlier three dimensional execution of these doors gave way to a simpler painted form during the New Kingdom.
False doors were often highly decorated and marked with the names and titles of the grave's owner. A representation of the deceased is also frequently found.

Flagpoles were often erected in pairs close to the façade of a temple or a palace wall, on either side of a gate or a window, e.g. on either side of the window of appearances shown below there are two poles with flags flying from them. They were made of fir stems [1] which were sometimes painted. Taller than the pylons to which they were anchored they reached normally about thirty metres, though at Karnak they were twice as tall.

Stone buildings were often erected on rock surfaces. When foundations had to be laid, the
building pit was first filled with water and the resulting horizontal
lines were marked on the walls. The water was then
removed and the pit filled with sand up to the marks. This was covered with several layers of broken
rock on which the rock slabs forming walls and pillars were placed.
The pavement in the Osiris temple at Tell Tebilla was laid on a 20 cm thick layer of sand [2].
At Karnak wall foundations never go deeper than two to three metres. At Luxor close to the river, walls were built on three layers of stone blocks each about 80 cm high and the brick foundations of the colonnades at the Ramesseum were less than two metres thick.
The relative weakness of these foundations, rising water-tables and other causes led to the collapse of most ancient buildings:
The alkaline groundwater at Karnak had dissolved the sandstone base of eleven huge pillars which crumbled on the 3rd October 1899. That they had endured for so long was thanks to the virtual absence of rain, the composition of the soil and the sun which bakes the Egyptian earth above the high-water line of the Nile almost to the hardness of rock.

Friezes, sculpted or painted horizontal decorative bands rather than the Greek and Roman entablature between architrave and cornice, were occasionally used to mark the upper limit of a wall. Animals like cobras were depicted (middle picture) as were kheker signs (on the right), abstractions of knots with which plant stalks were tied to wooden frames in order to create a wall.

Click on the picture excerpts for full size pictures.
Photos courtesy Jon Bodsworth

Most roofs of Egyptian buildings were flat and were used as additional floor space. In temples the roof was covered with tightly fitting stone slabs and in private houses they were waterproofed with mud, which, through the heat of the sun, became impervious to the rare, short rainfalls. The water had to run off - how this was problem was solved in the case of mud constructions is unknown, in stone temples on the other hand the solution dates back to the Old Kingdom: the water was collected in runnels running along the whole length of the roof and ending in a water spout. Since the time of Niuserre these spouts often took the shape of the fore part of reclining lions. But unlike in medieval gargoyles the water did not exit through their mouths but flowed off between their fore legs.[8]
The spouts were given the shape of lions as protective magic: the fierce animals were hoped to guard the buildings from the god Seth and his storms by getting rid of the rain water.[9]

Monolithic square stone pillars ending in a point, obelisks were erected in honour of the sun god Re, the oldest on a natural hill north of Heliopolis. During the 5th Dynasty the obelisk became the centre of the sun temple, later they are to be found standing in pairs by temple entrances. Their tips had the form of pyramidions and seem to have been covered by gilded copper sheets or the like.

She made (it) as her monument for her father Amon, lord of Thebes, erecting for him two great obelisks at the august gate (named): "Amon-is-Great-in-Terror," wrought with very much electrum; which illuminate the Two Lands like the sun......

Obelisks were generally erected in pairs on either side of a passage. But Thutmose IV, after finishing an obelisk begun by his grandfather Thutmose III, raised it as a

...... single obelisk in the forecourt of the temple over against Karnak, as the first beginning of erecting a single obelisk in Thebes .....

James Henry Breasted Ancient Records of Egypt, Part Two, § 627

The Heliopolis obelisks measured about 20.75 metres, those at Luxor somewhat more than 23 metres. Hatshepsut's Karnak obelisk was 33 metres tall. They weighed
often more than 250 tons. The biggest obelisk ever attempted was abandoned at the quarry when it cracked.
Made of granite, a rock harder than the metal tools available, obelisks had to be shaped and carved with the help of dolerite hammer stones.

Various theories of how they were erected have been proposed. They generally include an earthen ramp up which the obelisk would have been dragged base first, lowered slowly onto the foundation plate and then pulled upright.
A papyrus seems to point to the method used in lowering monuments

Empty the space that has been filled with sand beneath the monument of thy Lord, so that the monument may be established in its place.

However it was done, it was a major achievement. Hatshepsut boasted of having her obelisks cut, transported and erected in seven months.

Insufficient foundations, earthquakes and conquerors have caused the downfall of all but two obelisks. Since Imperial Roman times they have been collector's items and many have been shipped all over the world.

From simple, barely adorned granite columns, pillars evolved into stone plants: trunks of palm trees and bundles of lotus plants,
reeds or papyrus, often used side by side. Under Ramses II monumental forests of pillars were erected. The 5000 m² Hypostyle
Hall contained 134 sandstone pillars, the tallest of which were 23 metres tall and had a diameter of 3.5 m.
Because of their size, they had to be put together from half cylinders instead of the usual full cylinders. The columns were seemingly given their final shapein situ.
Pillars were either free-standing or engaged, sometimes they were purely ornamental, never more so than in the case of pillar reliefs carved into walls.

Pillars had also a symbolic role denoting stability and duration. Djed pillars, perhaps originating in posts to which ears of corn were tied, symbolized fertility. They became Osiris pillars which were the backbone of the god, supporting the sky and appeared first in Djoser's pyramid complex. Later they took the form of Osiris himself. Often the Djed pillars were just decorative without any structural
importance.
New Kingdom papyriform pillars with closed or open flower capitals were symbols for the sky crossed by the path of the sun: in the early morning the flowers are still closed but then open with the progress of the sun across the sky. They can be seen in the temples at Luxor.
Thutmose erected at Karnak two pillars which were symbolic for the united Egypt: one decorated with papyrus plants denoting Lower Egypt, the other Upper Egypt's lotus.
The head of the goddess Hathor was at times depicted on round or square pillars. The entrance hall of the temple dedicated to her at Denderah had 24 pillars crowned with heads of the goddess.

An abacus (from Greek abax, slab) was often inserted between pillar and architrave and was at times decorated with a cartouche.

Introduced at least as early as the Middle Kingdom, pylons were towerlike structures flanking temple entrances reminiscent of the mountains on the horizon between which the sun rose every morning. They were often solid structures with their interiors filled with rubble (the Amarna talatat on which scenes of life in Akhenaten's capital are depicted, survived thanks to being reused in this way), but many enclosed rooms and stairways. The tops of the pylon ended often in cavetto cornices. Flagpoles were attached to their fronts, and the flags could be attached to the poles through small windows. Pylons were often decorated with painted reliefs depicting the destruction of enemies of Egypt, reminding the temple visitors of the power of the king. The number of pylons differed from temple to temple, many having just one but the Amen temple at Karnak as many as ten.
On top of the gateway rituals connected with Amen-Re were performed. The importance of the pylons was mostly symbolic and possibly aesthetic: Linked to the protective goddesses Isis and Nephthys they were bastions against evil, protecting the god resting in the sanctuary.

Pyramidion, Egyptian benbenet - bnbn.t, is the name given to the tip of the obelisks and to the capstone placed on top of pyramids. It had the form of the pyramid which it capped and was covered with electrum or gold. It stood for the benben stone, according to the Egyptian mythology the primeval mound which emerged from the waters of chaos at Heliopolis and was the first firm object on which the rays of the sun fell.

Unlike many modern stairs which are often lightly built of either wood or steel, ancient Egyptian stairs were generally massive affairs made of bricks [4] or, in temples, of rock. As most towns were built in the plain, there was rarely need for wide public stairs of the kind found at Kahun.
Town houses sometimes had second or third floors, which could be reached by flights of stairs built of mud bricks or wood and the flat roofs of most houses were accessible and often used for sleeping and cooking.
Temples contained at times stairs

I filled his (Amon's) temple with august vases, in order to offer libations /////// I built their temples, wrought their stairways, restored their gates ...

An extreme, symbolic form of stairs may be Djoser's step pyramid, built perhaps to facilitate the deceased king's ascent to heaven.[6] (Only, if that was their purpose one may well wonder why this form of pyramid was abandoned)

These are often freestanding upright slabs of stone bearing inscriptions and at times reliefs. They may be commemorative, sometimes they were erected to indicate borders or boundaries. For instance, at least fourteen stelae marked the confines of Akhetaten. Stelae were placed at the southern border of Egypt with Nubia, and Thutmose is said to have left a border stela, which has never been found, in Syria.

Better known from ancient Greek temples, these raised platforms supporting rows of columns are also found in Egypt. They re-enforced the not very solid foundations the Egyptians were wont to build on. The court of Akhenaten's gm-pA-jtn temple at Karnak had a five metre wide stylobate to support colossal statues [5].

Egyptian monumental architecture was - with a few exceptions - based on trabeation, the post and lintel principle. This limited the covered spaces inside buildings to the width that could be bridged with the building materials used, in dwellings about three to four metres, the maximal plank length that could be cut from local wood. Ceilings exceeding this width had to be supported by posts. In temple hypostyle halls this resulted in forests of sculptured stone pillars (see above) supporting decorated architraves symbolizing the sky.

Occasionally kings had to show themselves to their subjects, perform public ceremonies like the dispensing of the Gold of Honour, but generally preferred to keep their distance. A solution was the use of the window of appearance let into the façade of the palace.

Source: BMFA 1964, No.328

In the above relief from Amarna the window is topped by a frieze of uraei, and above it, as sometimes happened in Egyptian depictions where objects, of which one was hidden behind the other, were pictured as one being above the other, is shown the columned hall which could be glimpsed by the populace through the window.

[1] The Lexikon der Ägyptologie translates aS as fir, lat. Abies Cilica, rather than cedar as did Breasted:

I inspected the great monuments which he made ////// great pylons on its either side of fine limestone of Ayan; august flagstaves were erected at the double façade of the temple of new cedar of the best of the Terraces (i.e. Mountain of Lebanon); their tops were of electrum.

[4] An early Ptolemaic account recording the supply of 15,840 bricks, more than would have been needed to build a workman's house. Cf brickmaking

For the stairway ---- (bricks) [Epeiph].Likewise for the stairway 1,500 ["].For the same 500 ["]For the royal gateway toward the north ------.Another stairway into the bath ------Reservoir for the old bath 1,000 ["]Total 15,840 ["]Mesore.For the wall which had been taken down in the palace 500 ["]And for the doors of the hemp factory 60 ["].Through Theopompos, for the servant Apollonios [[and for the 1,500 ["] rest of the stairways]].For the Arsinoeum 440 ["].Likewise for the Arsinoeum 600 ["]